The present invention relates to a cigarette lighter with a built-in battery checker (referred to hereinafter simply as the cigarette lighter/battery checker). More particularly, the present invention relates to a cigarette lighter/battery checker designed to install one or two indicating lamps together with a simple electric circuit therefor in a cigarette lighter for use in automobiles for the dual purposes of lighting up a cigarette and discriminating the degree of comsumption of a battery by visible change in brightness or color of illumination of the indicating lamp or lamps.
Automobiles are generally provided with a cigarette lighter which is actuated by a battery installed in the automobiles. However, this battery provides an electric source for not only the built-in cigarette lighter but also a self-starter, plugs, indoor and outdoor lights, a radio set, etc. If the degree of consumption of the battery goes beyond a certain limit, engines of automobiles would no longer be started up. In such case, a troublesome task such as exchange or recharging of the consumed battery is necessary, which burdens a driver with an unnecessary work, especially when he is on urgent business. On the other hand, consumption of a battery can be detected by measuring its voltage precisely with a precision voltammeter. However, consumption of a battery cannot easily be detected by measuring the voltage conveniently with an ordinary voltmeter. Accordingly, installation of a precision battery checker in automobiles is considered as a countermeasure for preventing excessive consumption of their battery. However, such installation makes the cost go up and requires additional space in the front or side instrument board of an automobile. These reasons make it difficult to put a battery checker into practice. Thus, there is a great demand by the automobile industries for developing a battery checker of a simple structure which can be installed without necessity of any additional space in the front or side instrument board.